Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics
related subjects. Usually these are held in the Building 6008
large Conference Room, at 3:00 pm on the chosen day, but times
and locations may vary. For more information, contact our seminar
chairman,

Magic and Semi-Magic Nature of the Tin Isotopes

Atomic nuclei are finite many-body quantum systems that possess shell structure with closures at Z
or N equal to 2, 8, 20, 28, 50, 82, or 126. The stable double-magic nuclei, i.e., closed shell in both proton
and neutron number, are limited to 4He, 16O, 40Ca, 48Ca, and 208Pb; radioactive ion beams can
provide access to additional nuclei that are potentially double magic such as 132Sn (Z=50, N=82).
Experiments on double-magic nuclei test the nuclear shell model and provide input to calculations of
properties of neighboring nuclei, many of which are radioactive and experimentally inaccessible. These
calculations rely on the inert core to reduce the many-body system to a size that makes the problem
tractable. New one-neutron transfer results of radioactive 133Sn and 135Te are presented, which
highlight the evolution from simplicity to relative complexity when moving from a system with one active
neutron outside of the double-magic 132Sn nucleus to a system with one active neutron and two active
protons. In addition, new Coulomb excitation data of the semi-magic tin isotopes are presented, which
highlight the way in which many nucleons act coherently (collectively) far away from doubly closed shells.
These recent experiments were conducted at the Holifield Radioactive Ion Beam Facility at ORNL using a
CsI-HPGe detector array (BareBall-CLARION) to detect scattered charged particles and emitted gamma
rays from the in-beam reactions.

*This research was sponsored by the Office of Nuclear Physics, U.S. Department of Energy.